1. Technical Field
The present invention relates to the field of metrology, and more particularly, to scatterometry overlay (SCOL) metrology targets.
2. Discussion of Related Art
Metrology targets are designed to enable the measurement of parameters that indicate the quality of wafer production steps and quantify the correspondence between design and implementation of structures on the wafer. Metrology targets as specific structures optimize the requirements for device similarity and for optical measurability. Scatterometry overlay (SCOL) targets are periodic structures which are used to produce diffraction patterns for metrology measurements. As wafer layers increase in number and the available space for metrology targets decreases, there is a constant requirement for more efficient use of target space.